| 摘要 |
An image forming apparatus has a photoconductive member, and a developing roller develops a latent image on the photoconductive member by a first alternating-current bias in the form of a rectangular wave. The following relationships are satisfied in calculating the duty ratio (D 1 ) of the first alternating-current bias using an application period of voltage in a direction to transfer the toner from the developing roller towards the photoconductive member as a positive period: a CV value in the number particle size distribution of the toner is <=25%, 4 mum<=Dt<=7 mum, 10<SUP>5 </SUP>Omega.cm<=PV<=10<SUP>9 </SUP>QOmegacm, 0.4 mum<=Ra<=1.5 mum, and 35%<=D 1 <=75%. where Dt denotes the volume average particle diameter of the toner, pv denotes the intrinsic resistance value of a developing roller surface, Ra denotes the arithmetic average roughness of the developing roller surface.
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